JPH09142576A - Introduction pipe of liquefied gas storage tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the gas pressure in a storage tank from decreasing owing to suction of the ambient gas. SOLUTION: An introduction pipe is vertically installed in a liquefied gas storage tank 1 to pour a liquefied gas 4 fed from the upper end 12A from the lower end 12B opened near the bottom of the storage tank 1 into the storage tank 1. At least one variable resistance 15 bringing a flowing resistant force to the liquefied gas flowing down from the upper end 12A to the lower end 12B, is arranged in the pipe at the vertical middle part. And a floating type adjusting structure 16 is provided in the outside of the pipe to set the variable resistance 15 at a large resistant position when the liquid level in the storage tank 1 is lower than the installed level of the variable resistance 15 and set the variable resistance 15 at a small resistant position when the liquid level in the storage tank 1 is higher than the installed level of the variable resistance 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an introduction pipe of a liquefied gas storage tank for pouring liquefied gas into a liquefied gas storage tank for storing a low temperature liquefied gas such as LNG or LPG.

[0002]

2. Description of the Related Art Conventionally, in a liquefied gas storage tank for storing low-temperature liquefied gas such as LNG and LPG, a piping system for pouring the liquefied gas into the storage tank is shown in FIG. In the figure, 1 is an airtight storage tank,
An introduction pipe 2 is arranged vertically inside the storage tank 1. The upper end 2A of the introduction pipe 2 is opened to the upper part inside the storage tank 1, and the lower end 2B is opened to the vicinity of the bottom part of the storage tank 1. Upper end 2A of the introduction pipe 2
Has a funnel-shaped opening so as to receive the liquefied gas flowing down from the lower end of the upper pipe (simplified by a line) 3 penetrating the roof 1a of the storage tank 1.

To flow the liquefied gas 4 into the storage tank 1,
A liquefied gas 4 is introduced from the upper pipe 3 to the upper end 2A of the introduction pipe 2. Then, the liquefied gas 4 flows down from the upper pipe 3 to the upper end of the introduction pipe 2, falls inside the introduction pipe 2, and flows into the storage tank 1 from the lower end thereof.

[0004]

By the way, in this type of storage tank, it is necessary to keep the gas pressure in the storage tank 1 constant.
It is a driving requirement. This is because, for example, when sending a liquid from a ship to a storage tank on the ground, if the gas pressure falls below a prescribed value, it will not be possible to return gas to the ship in place of the liquid.

However, in the case of a large-depth storage tank (for example, a storage tank having a depth of 30 meters), when the liquefied gas is introduced through the introduction pipe 2, the gas pressure in the storage tank 1 falls below the regulation. This is because the velocity of the liquefied gas 4 falling in the introduction pipe 2 becomes extremely large near the lower end 2B of the introduction pipe 2, and the surrounding gas is involved due to the influence thereof.

In view of the above circumstances, it is an object of the present invention to provide an introduction pipe for a liquefied gas storage tank which can prevent the gas pressure in the storage tank from being lowered due to the entrainment of ambient gas.

[0007]

According to a first aspect of the present invention, a liquefied gas is disposed vertically inside a liquefied gas storage tank, and a liquefied gas introduced from an upper end is flown into the storage tank from a lower end opening near the bottom of the storage tank. In the introduction pipe of the storage tank, at least one variable resistor that gives flow resistance to the liquefied gas falling from the upper end to the lower end is provided in the pipe in the middle in the height direction, and the liquid level in the storage tank is provided outside the pipe. When the level is lower than the installation level of the variable resistor, the variable resistor is set to the position of large resistance, and when the liquid level in the storage tank is higher than the installation level of the variable resistor, the variable resistor is set to low resistance. It is characterized in that an adjusting mechanism for setting the position is provided.

According to a second aspect of the present invention, in the first aspect of the present invention, the variable resistor is composed of a rotary plate that can be switched between a vertical posture in which the resistance is small and a horizontal posture in which the resistance is large depending on a rotational position. At the same time, the adjusting mechanism includes an arm that is orthogonal to the rotation axis of the variable resistor and that is connected to the protruding end of the rotation axis to the outside of the tube, and a float attached to the tip of the arm. The positional relationship between the float and the variable resistor is set so that the variable resistor has a horizontal posture when it is in the lower position, and the variable resistor has a vertical posture when the float is in the upper position due to buoyancy. And

A third aspect of the invention is characterized in that, in the second aspect of the invention, a stopper for restricting a movable range of the float is provided.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of a liquefied gas storage tank 1. Also in this liquefied gas storage tank 1, the introduction pipe 12 is vertically arranged inside the storage tank 1, and the upper end 12 of the introduction pipe 12 is
The liquefied gas 4 introduced from A is poured into the storage tank 1 from the lower end 12B opening near the bottom of the storage tank.

The introduction pipe 12 has a liquefied gas 4 falling from the upper end 12A to the lower end 12B in the pipe in the middle portion in the height direction.
One variable resistor 15 is provided to give a flow resistance to the. In the case of this embodiment, the installation level is set to a position which is about half of the liquid level 4H when the liquid is full (a = b in the figure). An adjusting mechanism 16 that controls the variable resistor 15 is provided outside the introducing pipe 12. When the liquid level in the storage tank 1 is lower than the installation level of the variable resistor 15, the adjusting mechanism 16 sets the variable resistor 15 to a position where the resistance is large, and the liquid level in the storage tank 1 is variable. The variable resistor 15 is set to a position where the resistance is small when the level is higher than the installation level.

The variable resistor 15 and the adjusting mechanism 16 will be described in detail with reference to FIG.
It is composed of a rotatable disc (rotary plate) having a diameter smaller than the inner diameter of 2, and a gap through which the liquefied gas flows is secured between the inner circumference of the introduction pipe 12 and the variable resistor 15. Since the variable resistor 15 is composed of a circular plate, by changing the rotational position, the flow resistance becomes small in the vertical posture and becomes large in the horizontal posture.

The adjusting mechanism 16 has a Y-shaped arm 18 which is orthogonal to the rotary shaft 17 of the variable resistor 15 and which is connected to the protruding end 17a of the rotary shaft 17 to the outside of the tube, and a bifurcated portion at the tip of the arm 18. It is made up of a float 19 that is sandwiched and attached. In this case, when the float 19 is at its lower position (position indicated by a chain double-dashed line) due to its own weight, the variable resistor 15 is in a horizontal posture, and when the float 19 is at an upper position (position indicated by a solid line) due to buoyancy, the variable resistor 15 is The positional relationship between the float 19 and the variable resistor 15 is set so as to be in a vertical posture.
In addition, a stopper that restricts the movable range of the float 19 to a position where the arm 18 abuts so that the float 19 moves only in a range of approximately 90 degrees between a lower position shown by a chain double-dashed line and an upper position shown by a solid line. 20, 21 are provided.

Next, the operation will be described mainly with reference to FIG. When the liquid level 4L is lower than the variable resistor 15, FIG.
As shown in (a), since the float 19 is lowered to its lower position by its own weight, the variable resistor 15 is in a horizontal posture with a large resistance. Further, when the liquid level 4L is higher than that of the variable resistor 15, as shown in FIG. 3B, the float 19 is lifted to the upper position by buoyancy, so that the variable resistor 15 is in a vertical posture with low resistance.

With the liquid level 4L in the storage tank 1 being low,
When the liquefied gas 4 is introduced into the upper end 12A of the introduction pipe 12, the liquefied gas 4 drops a large head, so that the falling speed becomes large in the vicinity of the lower end 12B and there is a possibility that the surrounding gas is entrained and the gas pressure is lowered. In this embodiment, FIG.
As shown in (a), the variable resistor 1 is provided in the middle of the introduction pipe 12.
Since 5 exists in a state of large resistance (horizontal posture), the liquefied gas 4 that falls falls on the variable resistor 15 and is decelerated. Therefore, since the speed of the liquefied gas 4 becomes slower, the entrainment of the ambient gas is suppressed and the decrease in the gas pressure in the storage tank 1 is suppressed.

Further, when the liquid level 4L in the storage tank 1 becomes higher than that of the variable resistor 15, the drop speed problem disappears due to the increase in the liquid level in the introduction pipe 12, and the problem of reduction of the inflow amount due to the flow resistance occurs. It appears, but in that case, Fig. 3 (b)
As shown in FIG. 5, the variable resistor 15 is set in a low resistance state (vertical posture), so that the flow resistance becomes small and the introduction ability of the liquefied gas 4 is not lowered.

In this embodiment, since the variable resistor 15 is controlled by the weight of the float 19 and the buoyancy force, no external power is required, the structure is simple, and the cost can be easily realized. Further, since the movable range of the float 19 is restricted by the stoppers 20 and 21, the variable resistor 15
Can be reliably positioned in the horizontal posture and the vertical posture, and the operation can be stabilized.

In the above embodiment, only one variable resistor 15 with the adjusting mechanism 16 is provided at the intermediate point in the height direction, but it may be provided at an appropriate intermediate level. A plurality of intermediate levels may be provided.
Then, the speed can be reduced for each installation level of the variable resistor 15, so that the gas entrapment can be more effectively suppressed.

Further, the shape of the variable resistor 15 and the adjusting mechanism 16 for operating the variable resistor 15 by the float 19.
Can be variously changed.

[0020]

As described above, according to the invention of claim 1, since the variable resistor is set at the position of large resistance when the liquid level is low, the falling speed of the liquefied gas can be slowed down. As a result, the gas entrainment can be suppressed, and a decrease in the gas pressure in the storage tank can be prevented. Further, when the liquid surface level becomes high, the variable resistor is set to a position where the resistance is small, so that the introduction capacity of the liquefied gas is not deteriorated.

According to the invention of claim 2, the attitude of the variable resistor is controlled by the weight of the float and the buoyancy.
It requires no external power and can be easily implemented at low cost.

According to the invention of claim 3, since the movable range of the float is regulated by the stopper, the operation can be stabilized.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an overall configuration of an embodiment of the present invention.

FIG. 2 is a perspective view showing a main configuration of the same embodiment.

FIG. 3 is an explanatory view of the operation of the embodiment, in which (a) shows a state when the liquid level is low and (b) shows a state when the liquid level is high.

FIG. 4 is a side sectional view showing a conventional example.

[Explanation of Codes] 1 Storage tank 4 Liquefied gas 4L Liquid level 12 Inlet pipe 12A Upper end 12B Lower end 15 Variable resistor 16 Adjusting mechanism 17 Rotating shaft 18 Arm 19 Float 20, 21 Stopper

Claims (3)

[Claims] 1. A vertical arrangement inside a liquefied gas storage tank,
In the introduction pipe of the liquefied gas storage tank, in which the liquefied gas injected from the upper end opens near the bottom of the storage tank and flows into the storage tank, the flow resistance to the liquefied gas falling from the upper end to the lower end is introduced into the pipe in the middle in the height direction. At least one variable resistor to be provided is arranged, and when the liquid level in the reservoir is lower than the installation level of the variable resistor outside the pipe, the variable resistor is set to the position of large resistance, An introduction pipe of a liquefied gas storage tank, comprising an adjusting mechanism for setting the variable resistor to a position where the resistance is low when the liquid level is higher than the installation level of the variable resistor. 2. The variable resistor is composed of a rotary plate that can be switched between a vertical posture in which the resistance is small and a horizontal posture in which the resistance is large according to a rotational position, and the adjusting mechanism is configured to It consists of an arm that is orthogonal to the axis of rotation and connected to the protruding end of the axis of rotation, and a float attached to the tip of the arm.When the float is in its lower position due to its own weight, the variable resistor is in a horizontal position. 2. The introduction of the liquefied gas storage tank according to claim 1, wherein the positional relationship between the float and the variable resistor is set so that the variable resistor takes a vertical posture when the float is in an upper position due to buoyancy. tube. 3. The introduction pipe for a liquefied gas storage tank according to claim 2, further comprising a stopper for restricting a movable range of the float.